Cellular Origin and Pathophysiology of Chronic Lymphocytic Leukemia

The cellular origin of chronic lymphocytic leukemia (CLL) is debated. Transcriptome analysis of CLL and normal peripheral blood and splenic B cell subsets displayed highest similarity of CLL to mature CD5+ B cells. We identified a distinct CD5+CD27+ post-germinal center B cell subset, and revealed that immunoglobulin V gene mutated CLL are more similar to mutated CD5+ B cells, whereas unmutated CLL are more related to unmutated CD5+ B cells. Stereotyped immunoglobulin V gene rearrangements were significantly enriched among CD5+ B cells, providing further genetic evidence for a derivation of CLL from CD5+ B cells. Moreover, we identified deregulated expression patterns providing novel insights into the pathophysiology of CLL, including downregulation of EBF1 and KLF family members.

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Seifert M, Sellmann L, Bloehdorn J, Wein F, Stilgenbauer S, Dürig J, Küppers R